Modelling of the hydraulic power take-off system at the wave-to-energy station installed in Gaza Strip

Wave energy from seas and oceans is among the most promising sources of renewable energy. A point absorber wave energy converter (WEC) was constructed at the Gaza-Palestine fishing port. A hydraulic circuit was used as the Power Take-Off (PTO) system to convert kinetic energy from floaters to useful electricity. The hydraulic PTO is well suited for dealing with the sea wave’s excessive forces applied on the WEC’s floaters at low frequencies. The efficiency of the PTO, and subsequently the WEC, depends on many parameters and operating conditions. Developing a control system is essential for enhancing PTO efficiency. The purpose of this study was to simulate both the hydraulic and control systems with the future aim to optimize the PTO by developing a control system and modifying the hydraulic circuit. SEIMENS SIMCENTER AMESIM software was used to replicate the installed hydraulic PTO. The main advantage of SIMCENTER AMESIM was the ability to deal with complex input data coming from irregular sea waves. The model was validated by comparing the simulation results with experimental data. The input for the model was real data taken at the different wave conditions (wave height and angles) and power output. The comparison was based on pressure and flow rate behaviours at different locations of the hydraulic circuit. This was especially important for critical components such as the accumulator and the pressure compensating valve. Both have an important role in the stability and efficiency of the circuit by absorbing flow pulsation and regulating the variability of pressure, subsequently, smoothing the power delivered to the electrical generator. The results showed an identical behaviour between the experimental data and results from the simulation. The model will be used for continuous improvement of the circuit, and for developing an improved control strategy.